Matrix metalloproteinase gene expression in oral lichen planus: erosive vs. reticular forms.

Background Oral lichen planus (OLP) is an autoimmune disease of unknown aetiology. The pathogenesis is characterized by apoptosis of basal keratinocytes,triggered by contact between CD8+-activated lymphocytes and an unknown antigen expressed on the surface of the basal cells. Basement membrane (BM) degradation, which allows lymphocytes to migrate, involves proteolytic enzymes known as matrix metalloproteinases (MMPs). Objectives This study aimed to evaluate the expression of a series of MMPs in biopsies from OLP patients, to reveal correlations with different clinical forms of OLP. Methods Twenty-six patients diagnosed with OLP (14 reticular and 12 erosive) were studied, together with seven healthy patients as negative controls. Results Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the overall levels of expression of MMP mRNAs were higher in erosive lichen planus (E-OLP) than in the reticular forms (R-OLP). Moreover, MMP-1 and MMP-3 may be principally associated with erosion development. The expression of specific tissue inhibitors of metalloproteinases (TIMPs) was also evaluated. Conclusions The different clinical appearances of OLP are associated with significant differences in MMP mRNA levels.